1. Field of the Invention
The present invention relates to a semiconductor device and a method for manufacturing the same.
2. Description of the Related Art
The history of developing semiconductor devices having transistors using semiconductors has been a history of the challenge of providing higher performance semiconductor devices at lower cost.
One of methods for improving the performance of semiconductor devices is to improve crystallinity of a semiconductor.
Single-crystal semiconductors have the highest crystallinity.
Single-crystal semiconductor wafers, SOI (Silicon on Insulator) substrates, and the like are given as substrates for single-crystal semiconductors.
However, such substrates have disadvantages of high cost. The disadvantages are more significant as the substrates have larger area.
On the other hand, semiconductor devices using semiconductors formed on low-cost substrates (for example, glass substrates) by a film formation method are given as low-cost semiconductor devices in which larger substrates are suitably used.
Further, regarding a semiconductor device using a semiconductor formed on a substrate by a film formation method, there have been attempts to provide higher performance semiconductor devices at low cost, in which crystallinity of a semiconductor is improved (for example, Reference 1: Japanese Published Patent Application No. H7-130652).
However, it is very difficult to make a perfect single-crystal semiconductor from a semiconductor formed on a substrate by a film formation method.
In response, there have also been attempts to form a single-crystal semiconductor on a low-cost substrate by attaching a single-crystal semiconductor onto a low-cost substrate (Reference: Japanese Published Patent Application No. H11-163363).